sedimentary
Diatomite
Diatomaceous Earth (mostly SiO2·nH2O)
Hardness: 1-1.5 (Mohs), Color: White, cream, or light grey, Luster: Dull or earthy, Texture: Fine-grained, friable, and porous, Specific Gravity: 1.9-2.35
- Hardness
- 1-1
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Physical properties
Hardness: 1-1.5 (Mohs), Color: White, cream, or light grey, Luster: Dull or earthy, Texture: Fine-grained, friable, and porous, Specific Gravity: 1.9-2.35
Formation & geological history
Formed by the accumulation of the siliceous remains (frustules) of diatoms, which are microscopic unicellular algae, in marine or lacustrine environments.
Uses & applications
Used as a filtration aid, mild abrasive in toothpastes/metal polishes, absorbent for liquids, insecticide (mechanical action), and thermal insulator.
Geological facts
Diatomite is so light and porous that dry specimens can often float on water briefly. It was used by Alfred Nobel to stabilize nitroglycerin to create dynamite.
Field identification & locations
Identify in the field by its very light weight, ability to easily powder when scratched, and a tendency to stick to the tongue due to extreme porosity. Found in ancient lake beds and seafloors.
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